Leak test passed but water is leaking out

hello everyone,

I don’t know where to put this topic, so I’m just writing here because it’s also about the company.

Last Friday, a leak test was done at our place and a leak test for the drain outside and inside the house was carried out. When I arrived, he told me the test was passed, but they noticed water is leaking out from under the front door, or rather, under the screed is already full of water. Yesterday, our site manager drilled a hole through the screed in the living room and saw that it is already really wet underneath (besides, he also drilled through a cable for the bus system...).
And now the opinions of the construction company and the plumbing company are that the man who did the leak test made a mistake. It could be that he put in too much pressure and that’s why water is leaking out of the connection of the wastewater pipes. Because the drain is tight, the water pipe was also tested, no problems there.
My question is, if it is eventually found that the fault is with the leak tester, can we as the client demand compensation? Is it best to go to a lawyer or an expert? Who has experience with this?
This is just nonsense, after 8 months the house is almost finished, kitchen, stairs, flooring all ordered and should come in 2 weeks, and we are already ready to move at the end of March, but suddenly something like this happens, it breaks my heart...
Hope someone has experience and can help us. Thanks in advance.

Best regards from Warstein

As always: Who has which contract with whom and who commissioned the leak tester?

I am not yet convinced that the wastewater is to "blame" for water in the screed. What about the fresh water pipes and heating pipes?

lawyer !

Always just lawyer, lawyer....

First determine the cause.

As always: Who has what contract with whom and who commissioned the tightness tester?

I am not yet convinced that the wastewater is to "blame" for the water in the screed. What about the fresh water pipes and heating pipes?

Hello, thank you for the answer. The heating and water pipes are all fine. The underfloor heating has been running since Christmas 2017, for 3 months now without any problems, I installed it myself with a technician, basically helped. They also worked on the water pipe with a pressure gauge over the weekend, there was no loss either.

lawyer!

Thank you. Once it is determined who is at fault.

Always just lawyer, lawyer.... First find out the cause.

Thank you. Exactly, I will wait first. Then immediately to a lawyer.